From: Baolin Wang Date: Tue, 20 Aug 2024 09:49:14 +0000 (+0800) Subject: mm: khugepaged: use the number of pages in the folio to check the reference count X-Git-Tag: v6.12-rc1~115^2~206 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d6b8f296e8d74d685627fd746558745c13b8bd32;p=thirdparty%2Fkernel%2Flinux.git mm: khugepaged: use the number of pages in the folio to check the reference count Use the number of pages in the folio to check the reference count as preparation for supporting shmem mTHP collapse. Link: https://lkml.kernel.org/r/9ea49262308de28957596cc6e8edc2d3a4f54659.1724140601.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Acked-by: David Hildenbrand Cc: Barry Song <21cnbao@gmail.com> Cc: Hugh Dickins Cc: Matthew Wilcox Cc: Ryan Roberts Cc: Yang Shi Cc: Zi Yan Signed-off-by: Andrew Morton --- diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 76f05215ee87e..e015c94eba09d 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1988,9 +1988,9 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, VM_BUG_ON_FOLIO(folio != xa_load(xas.xa, index), folio); /* - * We control three references to the folio: + * We control 2 + nr_pages references to the folio: * - we hold a pin on it; - * - one reference from page cache; + * - nr_pages reference from page cache; * - one from lru_isolate_folio; * If those are the only references, then any new usage * of the folio will have to fetch it from the page @@ -1998,7 +1998,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, * truncate, so any new usage will be blocked until we * unlock folio after collapse/during rollback. */ - if (folio_ref_count(folio) != 3) { + if (folio_ref_count(folio) != 2 + folio_nr_pages(folio)) { result = SCAN_PAGE_COUNT; xas_unlock_irq(&xas); folio_putback_lru(folio); @@ -2181,7 +2181,7 @@ immap_locked: folio_clear_active(folio); folio_clear_unevictable(folio); folio_unlock(folio); - folio_put_refs(folio, 3); + folio_put_refs(folio, 2 + folio_nr_pages(folio)); } goto out;